# Altium Scripts

## Capacitors by net pair

**Script:** `CapacitorsByNetPair.pas`

Finds all **two-pad components** on the PCB that share the same two nets (e.g. decoupling capacitors between VCC and GND). Outputs a JSON file with:

- **Key:** net pair (e.g. `"GND|VCC"`), sorted so the same pair is always grouped
- **Value:** for each net pair:
  - List of capacitors: designator, value string, package (footprint), and capacitance in farads
  - **Total capacitance** for that net pair (sum of all caps between those two nets)

### How to run

1. Open your **PcbDoc** in Altium Designer.
2. **DXP → Run Script…** (or **File → Run Script…** depending on version).
3. Browse to `CapacitorsByNetPair.pas` and run it.
4. Choose a save location for the JSON file when prompted.

### JSON output format

```json
{
  "GND|VCC": {
    "total_capacitance_F": 2.2e-05,
    "total_capacitance_str": "22uF",
    "capacitors": [
      {
        "designator": "C1",
        "value": "10uF",
        "package": "0805",
        "capacitance_F": 1e-05
      },
      {
        "designator": "C2",
        "value": "12uF",
        "package": "0805",
        "capacitance_F": 1.2e-05
      }
    ]
  },
  "GND|VDD": {
    "total_capacitance_F": 1e-06,
    "total_capacitance_str": "1uF",
    "capacitors": [
      {
        "designator": "C10",
        "value": "1uF",
        "package": "0603",
        "capacitance_F": 1e-06
      }
    ]
  }
}
```

### Protel PCB 2.8 ASCII — easier (Python, no Altium)

**Yes — Protel PCB 2.8 ASCII is easier.** It’s plain text, so you can parse it with Python and no OLE/binary handling. You don’t need Altium running.

1. **Export from Altium:** Open your PcbDoc → **File → Save As** (or **Export**) → choose **PCB 2.8 ASCII** or **Protel PCB ASCII** if your version offers it. Some versions use **File → Save Copy As** with format “PCB Binary/ASCII” or similar.
2. **Run the Python script** on the exported `.pcb` / `.PcbDoc` (ASCII) file:

   ```bash
   python3 capacitors_by_net_pair.py board.PcbDoc
   python3 capacitors_by_net_pair.py board.PcbDoc -o out.json
   ```

   **Input/output from .env:** Copy `.env.example` to `.env` and set `INPUT_FILE` and `OUTPUT_FILE`. The script reads these when the optional `python-dotenv` package is installed; CLI arguments override them. Without `.env`, you can still pass the input file and `-o` on the command line. By default the JSON is written to **`output/capacitors_by_net_pair.json`** (the `output/` directory is created if needed).

See **`capacitors_by_net_pair.py`** for the script. It parses COMP/PATTERN/VALUE and NET/PIN data from the ASCII file and produces the same JSON shape as the DelphiScript.

**Test file:** `tests/sample_protel_ascii.pcb` is a minimal Protel PCB 2.8 ASCII sample. Run:

```bash
python3 capacitors_by_net_pair.py tests/sample_protel_ascii.pcb -o tests/out.json
```

---

## Compare component locations (two Protel files)

**Script:** `compare_protel_locations.py`

Loads two Protel PCB 2.8 ASCII files and reports **which components have moved** between them. Component position is the centroid of pin coordinates. Output is written to `output/compare_locations.json` by default.

- **Moved:** designators with different (x, y) in file2, with old position, new position, and distance.
- **Only in file1 / only in file2:** components that appear in just one file.

**Usage:**

```bash
python3 compare_protel_locations.py board_v1.pcb board_v2.pcb
python3 compare_protel_locations.py board_v1.pcb board_v2.pcb -o output/compare_locations.json
```

Use **.env** (optional): set `FILE1`, `FILE2`, and `COMPARE_OUTPUT`; CLI arguments override them. Use `--threshold N` to set the minimum position change to count as moved (default 1.0).

**Test:** `tests/sample_protel_ascii.pcb` and `tests/sample_protel_ascii_rev2.pcb` (C1 and C2 moved in rev2):

```bash
python3 compare_protel_locations.py tests/sample_protel_ascii.pcb tests/sample_protel_ascii_rev2.pcb
```

### Notes

- Only components with **exactly two pads** (each on a net) and **designator starting with `C`** are included (treated as capacitors). To include all two-pad parts, edit the script and remove the `And (UpperCase(Copy(Component.Name.Text, 1, 1)) = 'C')` condition.
- Capacitance is parsed from the component **Value** parameter (e.g. `10uF`, `100nF`, `22pF`) and totalled in farads. Supported suffixes: F, mF, uF/µF, nF, pF.
- Package is taken from the component’s **Pattern** (footprint) name.
- If your Altium version uses different parameter or footprint property names, you may need to adjust the script (e.g. `DM_ComponentParameterName` / `DM_ComponentParameterValue`, or `Pattern` vs `Footprint`).